Automatic telephone system.



W. T. POWELL.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED FEB. 14, 1916. RENEWED JUNE 15, ms.

, l3 Hr M T Patented Feb. 4, 1919.

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AUTOMATIC TELEPHONE S YSTEM. APPLlCATlON FILED FEB-14,19l6. RENEWED JUNE15. 1918.

LQ9320 Patented Feb. 4, 1919.

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WINERED T. POWELL, OF CHICAGO, ILLINOIS, ASSIGNOR TO AUTOMATIC ELECTRICCOMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Mb. 4t, 1919.

Application filed February 14, 1916, Serial No. 78,164. Renewed June 15.1918. Serial No. 240,250.

To all whom. it may concern.

Be it known that 1, \Vrxreno T. lowmm, a citizen of the United States ofAmerica, and a resident of Chicago, (look county, and State of Illinois,have invented certain new and useful Improvements in Automatic TelephoneSystems, of which the following is a specification.

My invention relates to automatic telephone systems and moreparticularly to those systems which are made up, in part at least, ofpoly-station lines equipped for prepayment service.

In systems of the above character it is customary to use coin collectingdevices provided with a polarized relay which is operated by reversingthe direction of current flow in the line at the proper time in order torender the telephone instrument inoperative for talking purposes. A Thereversal of current flow is generally brought about by the response ofthe called subscriber; and, while the calling telephone is, as beforestated, rendered inoperative, it is not completely so, for the callingsubscriber is enabled to hear the called subscriber answer. He may thendeposit a coin of the correct denomination whereby his instrument isrestored to its original operative condition.

- The above described method of collecting for telephone calls is wellsuited to systems composed entirely of individual lines, or systemscomposed partly of polystation lines where it is not required to collectfor conversations between two subscribers on the same line. If, however,in the latter system, it is desired to collect for all calls, certaindifficulties appear which it is the object of my invention to overcome.

The problem to be solved arises from the fact that in a talkingconnection between two subscribers on the same line, both instrumentsare in the same relation to the line extending to the exchange. Itfollows that if the direction of current flow in the line is reversedboth instruments will ordinarily be affected in the same way and bothcalling and called subscribers will be required to deposit a coin. Sucha condition would clearly be very objectionable; for, aside from thefact that the connection would be paid for twice, the called subscriberwould not often be willing to pay for a connection which he did notoriginate.

My invention provides simple and efficient means whereby a poly-stationsubscriber, having been signaled by another subscriber on his line, isenabled to answer and converse without depositing a coin, the callingsubscriber, however, being required to deposit his coin in the regularmanner.

To accomplish the foregoing and other useful ends my invention comprisesmeans which will be hereinafter fully described, reference being had tothe accompanying drawings which, when taken in order with the lines atthe ends thereof in alinement, represent diagrammatically the apparatusand circuits used for completing a talking connection between twosubstations on the same poly-station line in a system embodying theprinciples of my invention.

Referring now to Figure 1, I have shown diagran-imatically at A and Atwo substations which may be of the general type of substation shown inBritish patent to T. G. Martin, N0. 1419 of 1910. The substation Aconsists essentially of the receiver 2, transmitter 3, switch hook 4,ringer 5, and condenser 6. Bein an automatic substation it is alsoprovidec with a pair of impulse springs 10 and 11 controlled through themedium of an impulse cam and finger hole dial (not shown). A pair ofshunt springs 12 and 13, closed whenever the finger hole dial is movedfrom its normal position, is provided for the purpose of shunting thetransmitter and receiver while sending impulses. Associated with thesubstation A is shown a coin collecting device which comprises amongother details a polarized relay having the windings 23 and 24, amarginal magnet 25, and a coin chute'22. The lever 18 is normally heldby the spring 21 against the upper edge of a slot in the coin chute 22through which it projects, in which position the arm 20 is adapted toengage the detent 19 on the lever 18. Arm 20 is rigidly attached to thearmature 26 which is pivoted at 27 and which is controlled by thewindings 23 and 24 of the polarized relay. The lever 18, when moved tothe left by arm 20 through the medium of detent 19, is adapted to closecontact springs 15 and 17 and to separate contact springs 15 and 16. Thema net 25, when sufficiently energized, is capafile of attracting thelever 18 against the tension of spring 21, thereby removing the detent19 from the path of arm 20.

Substation A may be substantially like substation A, except for theringer 5 which is somewhat different from ringer 5, the two ringersbeing adapted to respond to difi'erent kinds of ringing current. Theprinciple of selection depends preferably on what is commonly known asthe harmonic system, in which the ringers are tuned to respond todifferent frequencies of ringing current.

The line conductors 31 and 32, to which the two substations areconnected in parallel, extend to the exchange where they terminate inthe individual line switch C, which is of the general type disclosed inBritish patent to R. W. James, No. 26301 of 1906; being, however, morenearly of the particular type snown in U. S. Letters Patent No.1,078,690, granted J an. 17th, 1912 to Frank Newforth.

The line switch comprises among other details a plunger (not shown)attached to the end of a so-called plunger arm 40. The plunger arm 10and the cut-0d armature ll are controlled by the magnet 42 which has twowindings; one of which, the pull in winding 43, operates both theplunger arm and the cut-off armature; while the other, the holdingwinding 4a, is only strong enough to operate the cut-off armature and tohold the plunger arm in an operated position after it has been operatedby the pullin winding. When the plunger arm is operated, the plunger isforced into a bank of contact springs forcing the springs 49, 50, 51,and 52 into engagement with contacts 53, 5 1, 55, and 56, respectively.Although only one set of springs and contacts 19 to 56 inclusive) isshown, it is understood that each line switch is provided with aplurality of such sets, each set forming the terminal of a trunk lineextending to a selector switch. Each trunk line is connected in multiplewith the corresponding contacts of all the line switches oi the groupwhich is con- "rolled by the master switch D. The conductors s15, 16,and 17, are normal wires provided for the purpose of enabling otherlines in the exchange to connect with the line to which line switch (1individual. These conductors extend to multiple contact sets in thebanks of connector switches (not shown) adapted to connect with thegroup of lines of which the line of substation A is one. The line switchU is initially controlled by the subscriber through the medium of theline relay 33.

The master switch 10 is of the type disclosed in British patent to VJames, No. 26,301 cf 1906; being, however, more nearly of the particulartype disclosed in British patent to T. G. Martin, No 1419 0131910. Thefunction of the master switch, as is well known, is to maintain "theplungers of all the idle line switches in position before the terminalsof an idle trunk line.

The line switchl'l has access, through its 1 bank of contact springs, toa group of seneeaoao lector switches, one of which is shown at E. Theselector E may be of the general type of selector switch disclosed in U.S. Letters Patent No. 815,321, granted March 13,1906, to Keith, Ericksonand Erickson; except that the so-called side switch is omitted, and thecircuits are modified to enable the switch to operate in a system inwhich the central office apparatus is controlled by impulses deliveredover the two sides of the line in series. Among other details theselector E comprises a bank of contacts arranged in horizontal rows orlevels, which contacts are adapted to be engaged by a set of wipers 110,111, and 112 carried upon a shaztt (not shown) which has a verticalmovement controlled by the vertical magnet 109, and a rotary movementcontrolled by the "rotary magnet 108. The operation of the various partsof the switch is controlled through the medium of the double wound linerelay 100. Means for permitting the switch to be restored to normalposition is provided in the release magnet 10% which, upon energizing,withdraws the retaining pawls from the shaft. The contacts 120 and 121are closed only when the shaft has been raised one or more steps fromits normal. position. The relays 103 and 105 are slow acting.

The selector switch 13 has access through certain of its bank levels tosimilar selectors by means of which connections may be extended towardthe lines of other subscribers in the exchange, and it also has accessthrough a separate bank level to a group oi frequency selectors one ofwhich is shown at F (Fig. 2). The frequency selector T has access incommon with others of the same group, to the ringing relays shown at Mwhich are controlled by the solenoid in terrupter N. The ringingequipment comprising the frequency selector F, the ringing relays M, andthe interrupter N, is similar to the ringing equipment shown inAustralian Patent No. 13399 of 191a, although the circuits or thefrequency selector F are modified somewhat to enable it to operate inaccordance with the principles of my invention.

Among other details the frequency selector l comprises a plurality ofsets of contacts arranged in a horizontal circular bank and winch areadapted to be engaged by 16 166 l 16 me n lpers o, ant carried upon ashaft (not shown) which has a rotary relays such as the relays M (Fig.2). The

ringing current genera'tors R and R deliver ringing currents ofdifferent frequencies corresponding to the frequencies to which theringers 5 and 5 of the substations A and A will respond. Since I haveshown but two substations one set of ringing relays will be sufiicientto enable the subscribers at these substations to signal each other, butit is understood that a polystation line may have more than twosubstations eonnected thereto; and I have shown therefore two additionalsets of contacts indicated by reference characters 171, 172, and 173,and 1745, 175, and 176, for the purpose of giving the frequency selectorF access to additional ringing current combinations.

At N I have shown a solenoid interrupter which comprises among otherdetails a solenoid 300 which is adapted to raise a contactor 309 to thelevel of its uppermost set of contacts, after which the energizingcircuit of the solenoid is broken and the contactor descends to thebottom level of contacts, whereupon the operation is repeated. Thereference character 303 indi cates a dash pot or equivalent device forretarding the movement of the contactor. At l I have shown a connectingblock by means of which the interrupter N may lg made common to a numberof groups of ringing relays.

At B- 'I have shown a battery for supplying operating and talkingcurrent having its positive pole grounded at G. At B I have shown asecond battery having its negative pole grounded at G The purpose ofbattery B will be explained in 'the detailed specification.

Having given a general description of the apparatus I will now explainthe operation of the system shown herein. It will be explained how thesubscriber at substation A may, by suitable manipulation of hisinstrument, actuate the signal bell at substation A. It will beexplained further how the subscriber at substation A may remove hisreceiver and converse with the subscriber at substation A without havingto deposit a coin; the latter subscriber, however, being required todeposit his coin in the regular manner. Since much ofthe automaticapparatus shown herein is well known in the art, having been fullydescribed in the publications above referred.

to, its operation will be described in a more or less general manner,the details bein given only where they have to do with the operation ofmy invention.

Referring now to Fig. 1, the subscriber at substation A, upon removinghis receiver to initiate a call, completes an energizing circuit for theline relay 33 of the individual switch over the following pat-h: groundat G. contact springs 39 and 38, and line conductor 3.2 to one terminalof magnet 25, substation A, where the circuit divides, one branchextendingby way of magnet 25 and coils :23 and :Hsof' the polarizedrelay to impulse spring 11. and the other branch extending by way ofcontact springs 16 and 15, transmitter 3 and receiver 2 to impulses)ring 11. where the two branches unite an extend by way of impulsesprings 11 and 10. switch hook springs 9 and 8, line conductor 31.contact springs 36 and 37, and winding of line relay 33 to battery B.The line relay 33 is energized over the above circuit and uponattracting its armature 35. completes a circuit for the pull-in winding43. The pull: in winding, upon energizing its core. attracts the plungerarm 40 and the cut-off armature 41; the former. by means of its plunger,forcing the springs l952. inclusive, into engagement. respectively. withcontacts 5356, inclusive; and the latter disconnecting the lineconductors 32 and 31 from ground and battery. respectively, byseparating contact springs 38 and 39, and 36'and 37.

By the engagement of springs 49 and 52 with contacts 53 and 56.respectively, the line conductors 31 and 32 are extended to the doublewound line relay 100 of the selector E. The line relay 100 thereupon isenergized over a path which includes contact springs of the lineswitching relay 106, bank contacts and springs of the individual switchC, and the previously described circuitthrough substation A. Uponattracting its armature, the line rela completes a circuit from groundat (i for the slow acting relay 103,-which relay, upon energizing,prepares circuits for the vertical and rotary magnets 108 and 109 in thewell known manner, and also'completes a holding circuit for the lineswitch C which may be traced as follows: ground at G, contact springs116 and 117, contact 54, spring '50 and holding winding 44 of lineswitch C to battery 13. Although the circuit of the linerclay 33 hasalready been broken it retains its armature until after the abovedescribed circuit has been established. A branch of the holding circuitextends over conductor -15 to multiple test contacts in the banks ofconnectors havin access to the line of substation A,

tact 55 ground at G is extended to the contact in the master switch bankwhich corresponds to the trunk line seized by the line switch C, therebyoperating the master switch to move the plungers of the other idle lineswitches of the group to the next idle trunk in the well known manner.

The foregoing operations have all occurred in response to the removal ofthe receiver from the hook. lhe subscriber at substation A. may nowoperate his dial in accordance with the digit corresponding to the levelof the selector E in which are lo cated contacts which are terminals ofthe groups of frequency selectors, thereby breaking the continuity ofhis loop a number of times at the impulse springs 10 and 11. As a resultof these interruptions the line relay 100 is deener ized a correspondingnumber at times, sending an impulse at each deenergization from groundat G to the slow acting relay 105 and the vertical magnet 109 in series.'llhe vertical magnet, in response to these impulses, steps 11 the shaftuntil the wipers stand opposite t e desired horizontal level. The relay105, being slow acting, retains its armature during the series of im'pulses and closes a circuit for the test relay 107, which relay locksitself from ground at G and closes contact springs in the rotary magnetcircuit. At the end of the series of impulses the relay 105 deenergizes,thereby completing the circuit for the rotary magnet 108, whereupon thewipers 110, 111, and 112 are started rotating in search of a ,trunk lineextending to an idle frequency selector. As is well known, the rotarymagnet interrupts its own circuit and also the locking circuit of thetest relay at every energization, the contacts in the latter circuit,however, being short circuited by the test wiper 111 while passing overbusy or grounded test contacts. As soon, therefore, as the test wiperreaches an un rounded test contact the test relay 107 fa ls back andopens the rotary magnet circuit, thereby bringing the wipers to restupon the contacts of an idle frequency selector, assumed in this case tobe the one shown at F (Fig. 2). The test relay 107, upon denergizing,completes a circuit for the line switching relay 106, which latterrelay, upon energizing, disconnects the line conductors from the linerelay 100 and ex tends them, by way of wipers 110 and 112, bank contacts113 and 115, conductors 375 and 376, and contact springs of relays 1-55and 153 to the double wound line relay 150 of the frequency selector F.

The line relay 150 thereupon energizes over the previously tracedcircuit through the subscribers loop and by attracting 1ts armaturecompletes a circult'from ground at G to the slow acting relay 158. Relay158, upon energizing, prepares a circuit for the rotary magnet 156, andalso completes a meaeao new holding circuit which may be traced asfollows: ground at 6%, contact springs 181 and 180, conductor 377, bankcontact 114:, and wiper 111 to off normal contact spring 121, where thecircuit divides, one branch extending by Way of contact springs of thetest relay 107 and winding of the line switching relay 106 to battery B,and the other branch extending by way of contact 123 and interruptercontact 122 to wire junction 12%, where it joins the previouslydescribed holding circuit for line switch C.

The subscriber at substation A. may now operate his dial in accordancewith the digit which corresponds to the position of the required set ofcontacts in the bank of the frequency selector. It is understood ofcourse, that each poly-station subscriber has been instructed as to theproper numbers to call to signal each of the other parties on his line.As before, the operation of the dial results in interruptions of theline circuit, which interruptions result, in this case, in correspondingdenergizations of the line relay 150. At each deenergization the linerelay sends an impulse to the slow acting relay 159 and the rotarymagnet 156 in series over the following path: ground at G, contactsprings 182 and 188, contact springs 190 and 189, winding of relay 159,winding of rotary magnet 156,- and side switch wiper 163 in its firstposition to battery B. Since the ringing relays shown herein areconnected to the first set of bank contacts, the final digit to becalled is 1, and the rotary magnet receives one impulse, in response towhich the wipers 165, 166 and 167 are rotated into engagement,respectively, with bank contacts 168, 169, and 170. The slow actingrelay .159, as before stated, is energized in series with the rotarymagnet and, upon attracting its armature, completes a circuit for theprivate magnet 160 as follows: ground at G contact springs 188 and 187,and winding of private magnet 160 to battery B. At the end of theimpulse or series of impulses, as the case may be, the slow acting relay1-59 deenergizes, thereby breaking the circuit of the private magnetwhich in turn deenergizes and allows the side switch wipers to advancetotheir second position in the well known manner.

Connection has now been established with the group of ringing relays M.The next act of the subscrlber at substation A is to hang up hisreceiver, thereby breaking the circuit of the line relay 150 by openingswitch hook contact springs 8 and 9. Upon deenergizing, the line relay150 completes a circuit for relays 161 and 159 which may be traced asfollows: ground at G, contact springs 182 and 183, contact springs 190and 189, winding of slow acting relay 159, winding of relay 161, andside switch wiper 1,aos,eso

163 in its second osition to battery B. Upon energizing, re ay 159 againcompletes the energizing circuit of the private magnet, and also (sideswitch wiper 162 being in its second position) completes a circuitincluding relay 154 as follows: ground at G side switch 'wiper 162incits second position, contact springs 221 and 222, and winding ofrelay 154 to battery B. Relay 154, upon energizing, completes a newcircuit from ground at G14 for slow acting relay 158, and also preparesa circuit for the booster battery B. 7

Relay 161, energized in series with relay 159, as before stated.completes a circuit for the starting relay 311 as follows: ground at Gwinding of relay 311, bank contact 168, wiper 165, contact springs 186and 185, and winding of relay 153 to battery B. Relay 153 is a marginalrelay and will not operate in series with relay 311, which is preferablyof high resistance. Relay 311', upon attracting its armature. completesan initial energizing circuit for winding 302 of relay 320 of theinterru ter N over the following path: ground at 8, contact 325,contactor 309, contact 326, winding 302 of relay 320, common conductor316, armature 312, and contact 313 to battery B. Relay 320, uponenergizing. completes an independent circuit for its winding 302 bymeans of armature 306 and contact 308, and also completes a circuit forthe solenoid 300 as follows: ground at G, windings of solenoid 300,contact 305 armature 304, common conductor 316, armature 312, andcontact 313 to batterv B. Upon energizing the solenoid 300 raises thecontactor 309, thereby short circuiting in succession each of the setsof opposite interrupter contacts. but. without effect at this time,however, for the multiple contacts 331 are dead.

As the contactor reaches its extreme upward position it connectscontacts 329' and 330. thereby completing a circuit for the winding 301of relay 320 as follows: ground at G contact 330, contactor 309, contact329, winding 301 of relay 320, contact 305, armature 304, commonconductor 316, armature 312, and contact 313 to battery B. Relay 320' isdifferentially wound and accordingly retracts its armature therebybreaking the circuits of. both its windings and also the circuit of thesolenoid 300. Upon the cessationof current flow in the solenoid '300,the contactor 309 descends to its normal position.

In passing contact 328 a circuit is momentarily completed for theringing relay 315 as follows: ground at G, armature 306, con tact 307,multiple contact 331, contactor 309, contact 328, connecting block P,and .Winding to relay 315 to battery B. Upon energizing, relay315 shortcircuits the high resistance relay 311 by means of contact340 andarmature 341 thereby energizing relay 153 over a circuit which has beendescribed. At the same time relay 315 completes a circuit including theringingcurrent generator R which may be traced as follows: upper brushof ringing generator R contact 345, armature 344, bank contact 170,wiper 167, contact springs 198 and 199. Contact springs 206 and 204,conductor 376. bank contact 115, wiper 112, contact springs 131 and 132,contact 56, spring 52, line conductor 32, ringers 5 and 5 and condensersin series therewith in parallel (both receivers being hung up), lineconductor 31, spring 49, con tact 53, contact springs 133 and 134, wiper110. bank'contact 113. conductor 3T5, contact springs 201 and 202'.contact springs 196 and 195, wiper 166. bank contact 169, armature 342,and contact 343 to the lower brush of ringing generator R Ringer 5responds to ringing current in the above circuit thereby signaling thesubscriber at substation 11..

As the contactor 309 passes contact 327 ringing relay 314 is energizedmomentarily, whereby the above described ripging circuit is againco1npleted,-with the exception, however, that the ringing generator R issubstituted for the ringing generator R lin this latter'instance theringer 5 responds, thereby signaling the calling subscriber who is thusinformed that the ringing operation is proceeding satisfactorily. henthe contactor 309 reaches its bottom or normal position the circuit ofwinding 302 of relay 320 is again completed, whereupon the entireringing cycle repeats itself.

It will be seen from the foregoing that the ringing relays 314 and 315are energized alternately. each relay serving to connect its associatedringing generator to the set of bank contacts upon which the wipers 166and 167 .are resting. and at the same time sending a direct ground byway of wiper 165 to relay 153. which relay operates to disconnect thetwo sides of the line from the line relay and connect them to the wipers166 and 167. In order to allow the condensers 6 and 6 at the substationsto discharge after each application of the ringing current to the linethe relay 153 is made slow acting with the result that each time one ofthe ringing relays deinergizes the line is momentarily short circuitedby the conductor 350. This is done to guard against a possible actuationof relay 150 by condenser discharge immediately after relay 153denergizes.

Before proceeding with the operation it will be advisable to considerthe condition of the polarized relays at the substations A and A. Whenthe receiver was removed at substation A preparatory to making the call,a circuit was completed by the hook springs 8 and 9, whichcircuitincluded as one of its branches the magnet 25 and windings 23 and24 of the polarized relay in series, as has already been described. Thedirection of current flow in the above circuit is such that the arm 20is moved to the right until it reaches the position shown in thedrawing. The magnet 25 is marginal and is unable at this time to attractthe lever 18 against the tension of the spring 21. The position of thearm 20' at substation A will depend upon the direction of the currentwhich last flowed through the windings of the polarized relay. Theposition of arm 20' is, however, immaterial at this time.

Returning now to the frequency selector- F, it has been explained howthe relays 158, 159, 161, and 154- remain energized after the callingsubscriber at substation A has replaced his receiver. In addition it hasbeen ex lained how the side switch wipers are he d in their secondposition by the private magnet while the relay 153 operatesintermittently in conjunction with the ringing relays M to ring thecalling and called substations alternately.

Now when the subscriber at substation A removes his receiver in responseto the ringing of his bell, there is again completed, at the nextdenergization of relay 153, an energizing circuit for line relay 150,which circuit may be traced as follows: ground at G winding 151 of linerelay 150, contact springs 200 and 199, contact springs 206 and 204,conductor 376, bank contact 115, wiper 112', contact springs 131 and132, contact 56, spring 52, and line conductor 32 to one terminal ofmagnet .25 where the circuit divides, one branch extending by way ofmagnet 25. and coils 23 and 24 of the polarized relay to impulse spring11, and the other branch extending by way of contact springs 16' and 15,transmitter 3' and receiver 2 to impulse spring 11, where the'twobranches unite and extend by way of impulse springs 11 and 10, switchhook springs 9 and 8, line conductor 31, spring 49, contact 53, contactsprings 133 and 134, wiper 110, bank contact 113, conductor 375, contactsprings 201 and 202, contact springs 196 and 197, and winding 152 ofrelay 150 to battery B. Upon the completion of the above circuit thelower end of arm 20 at substation A is moved to the right by thepolarized relay until it reaches the position in which arm 20 ofsubstation A is shown. Magnet 25 is not sufficiently energized toattract the lever 18; therefore the detent 19 is in engagement with thelower end of arm 20'. At the exchange the line relay 150 of thefrequency selector F is energized and attracting its armature, breaksthe circuit of relays 159 and 161 and again completes the originalenergizing circuit of relay 158. Relay 161, upon deenergizing, opens theintermittent energizing circuit of relay 153 at contact springs 185 and186, these contact been reverse.

springs being also included in the circuit of the starting relay 311.Relay 159, upon 'deenergizing, breaks the circuit of the private magnet160 and also breaks the circuit of the slow acting relay 154. Theprivate magnet 160, upon denergizing, allows the side switch wipers toadvance to their third position in the well known manner. Instantly acircuit is completed for relay 155 as follows: ground at G", contactsprings 181 and 180, winding of relay 155, and side switch wiper 163 inits third position to battery B. Relay 155, upon attracting itsarmature, reverses the connections of the incoming line conductors 375and 376, and at the same time, rela 151 still holding its armatureattracted, the battery B is momentarily put in series with battery B,the resistance 161 being substituted for the lower winding of the linerelay 150. In this manner a booster impulse is transmitted over the lineto substation A, the circuit being as follows: ground at G negative poleof battery B, positive pole of battery B, resistance 1641, contactsprings 211 and 209, contact springs 203 and 201. conductor 375, bankcontact 113, wiper 110, thence over previously traced circuit to andthrough substation A and back to wiper 112, whence it extends by way ofbank contact 115. conductor 376, contact springs 20-1 and 205, contactsprings 196 and 197, winding 152 of relay 150, negative pole of batteryB, positive pole of battery B, ground at G to ground at G the startingpoint. It will be observed that the direction of current flow in theline has As a result of the simultaneous reversal of current and boosterimpulse the lower end of arm 20' is moved to the left and at the sametime the lever 18 is attracted bythe magnet25, which now receives enoughcurrent to draw the detent 19 from the path of the arm 20'. It followsthat the contact springs 15,'16, and 17 in the telephone circuit are notdisturbed. It

\is understood that the booster impulse is but momentary, the battery Band resistance 16% being cut out as soon as slow acting relay 151deinergizes and the lower winding of line relay 150 substitutedtherefor.

The ringing of this bell having ceased, the calling subscriber atsubstation Avis thereby apprised of the fact that the subscriber atsubstation A has answered. He will then remove his receiver also, againcompleting the hereinbefore traced parallel circuits through the magnet25 and winding of the polarized relay, and the transmitter and receiver.This time, however, the current flow is in the reverse direction, and asa result the lower end of arm 20 is moved to the left carrying with itthe lever 18 and thereby closing contact springs 15 and 17 andseparating contact springs 15 and 16. By the closing of contact springs15 and 17 the transmitter 3 is short circuited, and by the separation ofcontact springs 15 and 16 the previously described circuit throughreceiver 2 is opened. Since the contact springs 15 and 16 are shunted bythe small condenser 14, however, the calling subscriber is enabled tohear his party although he can not converse with him. The calling.subscriber may now: drop a suitable coin in the coin chute 22 therebyknocking the detent 19 out of engagement with the arm 20. As soon as thelever 18 is freed it is drawn to the right by the spring 17 which springseparates from spring 15 by its own ten- .sion and allows springs 15 and16 to again make contact thereby restoring the telephone to itsoperative condition.

The two subscribers may now converse without further effort, the voicecurrents taking the path shown in the heavy lines. Talking battery forthe transmitters is supplied from the double wound line relay 150 of thefrequency selector F. 7

When the conversation is over, both subscribers will hang up theirreceivers thereby breaking the circuit of the line relay 150 which, upondeenergizing', breaks the circuit of slow acting relay 158. Relay 158,upon deenergizing, removes ground from the holding circuit extendingback to the selector E and the line switch 0, whereupon these switchesare restored to their normal position in the well known manner. Relay158 also completes a circuit for the release magnet 157 of the frequencyselector as follows: ground at G contact springs 182 and 183, contactsprings 190 and 191, contact 192, ofi' normal spring 193, and releasemagnet 157 to battery B. Upon energizing the release magnet restores theshaft and side switch wipers to their normal position, the formeroperation breaking the re lease magnet circuit at the ofi normal spring183. In order to insure the complete restoration of the side switchwipers the contact point 194 is provided. When the shaft returns tonormal position, spring, 193 makes contact with contact 194 whereby, in

case the'side switch wipers are still in second position, "the releasemagnet is, energized momentarily by ground at G thereby moving the sideswitch wipers to their first or normal position.

It will be seen from the foregoing that I have devised a simple and.efiicient improvement in automatic telephone systems having theprepayment feature, whereby such systems may include polystation linesas well as individual lines. In my improved system a calling party linesubscriber is enabled to connect with every other subscriber in theexchange, including the other subscribers on thesame line, and isuniformly required to pay for each connection in advance by dropping acoin in a collecting mechanism provided for the purpose it beingunderstood that in no case is the calledsubscriber required to pay.

While I have described in the foregoing a certain specific embodiment ofmy invention, I do not wish to be held strictly to the exact formshownherein, for modifications will no doubt suggest themselves to personsskilled in the art. I desire, therefore, to include and have protectedby Letters Patent all forms and modifications of my invention which maycome within the scope of the appended claims.

\Vhat I claim as my invention is:

1. In a telephone system, a station and a line therefor, a device forrendering said station inoperative for talking purposes, an automaticmechanism, means under the control of said station forexte'nding saidline into connection with said mechanism, means associated with saidmechanism for operating said device, and means at said stationforpreventing the operation of said device.

2. In a telephone system, a station and a line therefor, a reversecurrent controlled said mechanism, means associated with said mechanismfor reversing the direction of current flow in said line to operate saiddevice, and means at said station for preventing the operation of saiddevice.

3. In a telephone system, a station and a line therefor, a device forrendering said station inoperativ for talking purposes, an automaticmechanism, means under the control of said station for extending saidline into connection with said mechanism, means associated with saidmechanism for operating said device, means at said station forpreventing the operation of said device, said last means normallyinoperative, and manually controlled means for restoring said station tooperativecondition.

4. In a telephone system, a station and a line therefor, a, reversecurrent controlled device for rendering said station inoperative fortalking purposes, a source of current for said line, an automaticmechanism, means under the control of said station for extending saidline into connection with said mechanism, means associated with saidmechanism for reversing the direction of current flow in said line tooperate said device, means at said station for preventing the operationof said device, said last means normally inoperative, and manuallycontrolled means for restoring said station to operative condition.

5. In a telephone system, a station and a line therefor, a device forrendering said station inoperative for talking purposes, an automaticmechanism, means under the control of said station for extending saidline into connection with said mechanism, means associated with saidmechanism for operating said device, and means at said station forpreventingthe operation of said device, said last means comprising anormally inoperative magnet serially connected in a branch of said line.

6. In a telephone system, a station and a line therefor, a. reversecurrent controlled device for rendering said station inoperative fortalking purposes, a source of current for said line, an automaticmechanism, means under the control of said station for extending saidline into connection with said mechanism, means associated with saidmechanism for reversing the direction of current flow in said line tooperate said device, and means at said station for preventing theoperation of said device, said last means comprising a normallyinoperative magnet serially connected in a branch of said line.

7. In a telephone system, a station and a line therefor, a device forrendering said station inoperative for talking purposes, a

source of current for said line, an automatic mechanism, means under thecontrol of said station for extending said line into connection withsaid mechanism, means associated with said mechanism for operating saiddevice, meansat said station for preventing the operation of saiddevice, said last means comprising a normally'inoperative magnetserially connected in a branch of said line, and means for increasingthe current flow in said branch to operate said magnet.

8. In a telephonesystem, a station and a line therefor, a reversecurrent controlled device for rendering said station inoperative fortalking purposes, a source of current for said line,,anautomaticmechanism, means under the control of said station for extending saidline into connection with said mechanism, means associated with saidmechanism for reversing the direction of current flow in said line tooperate said de vice, means at said station for preventing the operationof said device, said last means comprising a normally inoperative magnetserially connected in a branch of said line,

and means for increasing the flow of current in said branch to operatesaid magnet.

9. In a telephone system, a station and a line therefor, a device forrendering said station inoperative for talking purposes, an automaticmechanism, means under the control of said station for extendingsaid'line into connection with said mechanlsm, means associated withsaid mechanism for operating said device, means at said station forpreventing the operation of said device, said last means comprising anormally inopera tive magnet serially connected in a branch of saidline, and coin controlled means for restoring said station to operativecondition.

10. In a telephone system, a station and a line therefor, a reversecurrent controlled device for rendering said station inoperative fortalking purposes, a source of current for said line, an automaticmechanism, means under the control-of said station for extending saidline into connection with said mechanism, means associated with saidmechanism for reversing the direction of ourrentfiow in said line tooperate said de vice, means at said station for preventing the operationof said device, said last means comprising a normally inoperative magnetserially connected in a branch of said line, and coin controlled meansfor restoring said station to operative condition.

11. In a telephone system, a line, a plurality of stations in bridgethereof, a reverse current controlled device at each station forrendering its associated station inoperative for talking purposes, asource of current for said line, a selective signaling mechanism, meansunder the control of a calling one of said stations for extending saidline into connection with said mechanism and for initiating theoperation thereof, means associated With said mechanism for reversingthe direction of current flow in said line to operate said devices, andmeans at each substation for preventing the operation of its associateddevice.

12. In a telephone system, a line, a. plurality of stations in bridgethereof, a reverse current controlled device at each station forrendering its associated station inoperative for talking purposes, asource of current for said line, a selective signaling mechanism, meansunder the control of a calling one of said stations for extending saidline into connection with said mechanism and for initiating theoperation there of, means associated with said mechanism for reversingthe direction of current flow in said line to operate said devices,means at each substation for preventing the operation of its associateddevice, saidlast means normally inoperative, and manually controlledmeans at each of said stations for rendering its associated stationoperative for talking purposes.

13. In a telephone system, a line, a plurality of stations in bridgethereof, a reverse current controlled device at each station forrendering its associated station in operative for talking purposes, asource of current for said line, a selective signaling mechanism, meansunder the control of a calling one of said stations for extending saidline into connection with said mecha-- nism and for initiating theoperation thereof, means associated with said mechanism for reversingthe direction of current flow in said line to operate said devices, and

-means at each substation for preventing the operation of its associateddevice, said last means comprising a normally inoperative magnet foreach of said stations serially connected in a branch of said line.

14. In a telephone system, a line, a plurality of stations in bridgethereof, a reverse current controlled device at each station forrendering its associated station inoperative for talking purposes, asource of current for said line, a selective signaling mechanism, meansunder the control of a calling one of said stations for extending saidline into connection withsaid mechanism and for initiating the operationthereof, means associated with said mechanism for reversingthe'direction of current flow in said line to operate said devices,means at each substation for preventing the operation of its associateddevice, said last means comprising a normally inoperative magnet foreach of said stations serlally .connected in a branch of said line, andmeans for increasing the current flow 1n sald branch to operate one ofsaid magnets.

15. In a telephone system, a line, a plurality of stations in bridgethereof, a reverse current controlled device at each. station forrendering its associated station 1noperative fortalking purposes, asource of current for said line, a selectlve signaling mechanism, means.under the control or a calling one of said stations for extendlng saidline into connection-with said mechanism and for initiating theoperation thereof, meansassociated with said mechan sm for reversing thedirection of current flow in said line to operate said devices, means ateach substation for preventing the operation of its associated device,-said last means comprising a normally inoperative magnet for each ofsaid stations serially, connected 1n a branch of said line, means forncreasmg the current flow in said branch to operate one of said magnets,and coin controlled means at each of said stations for restoring itsassociated station to operative condition;

16; In a telephone system, a subscribers station and a line therefor, aplurality of branches of said line at said station, a microphone and areceiver in one branch, a reverse current controlled magnet in anotherbranch operable to exclude said microphone from said first branch, and asecond mag-.

net operative to render ineflectual the operation of said first magnet.

17. In a telephone system, a subscriberls station and a line therefor, aplurality of branches of said line at said stati an, a microphone and areceiver ,in one branch, a reverse current controlled magnet in anotherbranch operable to exclude said microphone from said first branch, asecond magnet operative to render ineffectual the operation of saidfirst magnet, an automatic switch accessible to said line, and meansassociated with said switch for operating said magnets.

-18. In a telephone system, a subscribers station and a line therefor,automatic switches controllable over said line from said station, aplurality of branches of said line at said station, a microphone and areceiver in one branch, a magnet in another branch operable through themedium of one said switches to exclude said microphone from said firstbranch, and a second magnet controllable through the medium of the sameswitch for rendering the operation of said first ma et inefiectual.

l9. In a te ephone system, a subscribers station and a line therefor,automatic switches controllable over said line from said I station, aplurality of branches of said line magnet ineffectual and manuallycontrolled means for also rendering the operation of said first magnetinefl'ectual.

20.'In a telephone system, a party line and a plurality of stations inbrid e thereof, a reversecurrent controlled evice at each station forrendering it inoperative for talking purposes,- a source of current forsaid line a selective signaling mechanism, means under the control of acalling one of said stations for extending said line into connectionwith said mechanism and for initiating the operation thereof, a normallyinoperative magnet in a bridge of said line at each of said stations forpreventing the effectualoperation of its associated device, meansassociated with said mechanism for momentarily increasing the currentflow in said line to operate the said magnet at a called one of saidstations, and means associated with said mechanism for reversing thedirection of current flow in said line to operate thesaid device at thesaid calling each station for rendering it inoperative for talkingpurposes, a source of current for said line, a selective signalingmechanism, means under the controlof a call ng one of said stations forextendmg said line into connection with saidmechanism and for initiatingthe operation thereof, a normally inoperative magnet in a bridge of saidline at each of said stations for preventing the effectual operation ofits associated device, means associated with said mechanism formomentarily increasing the current flow in said line to operate the saidmagnet at a called one of said stations, and means associated with saidmechanism for reversing the direction of current flow in said line tooperate the said device at the sa1d calling station, said currentreversing means and said current increasing means controlled by the saidcalled station.

22. In a telephone system, a party line and a plurality of stations inbridge thereof, a reverse current controlled device at each of saidstations for rendering its associated station inoperative for talkingpurposes, a normallv inoperative magnet in a bridge at each of saidstations for rendering the operation of its associated deviceineffectual, a source of current for said line, a selective signalingmechanism accessible to said line, means under the control of a firstone of said stations for operating said mechanism to signal a second oneof said stat-ions, means associated .with said mechanism for increasingthe current flow in said line to operate the said magnet at said secondstat1on, and means associated with said mechanism for reversing thedirection of current flow in said line to operate the said de vices atsaid first and second stations.

23. In a telephone system, a line and a plurality of stations in bridgethereof, a reverse current controlled device in bridge of the lineat-each station for rendering its associated station inoperative fortalking purposes, a normally inoperative magnet in bridge of the line ateach station for rendering the operation of its associated deviceineffectual, a source ofcurrent for said line, a selective signalingmechanism, means controllable from a calling one of said stations forextending said line into connection with said mechanism, meansresponsive to the opening of said line at-the said calling station foroperating said mechanism to signal a called one of said stations, andmeans responsive to the closing of said line at the said called stationfor momentarily increasing thecurrent flow in said line to operate thesaid magnet at the called station and for reversing the direction ofcurrent flow in said line. to operate the said device at the callingstation when the line is again closed thereat.

24. In a'telephone system, a line and a plurality of stations in bridgethereof, a reverse current controlled device in bridge of the line ateach station for rendering its associated station inoperative fortalking purposes, a normally inoperative magnet in bridge of the line ateach station for rendering the operation of its associated deviceinetfectual, a source of current for said line, a selective signalingmechanism, means controllable from a calling one of said stations forextending said line into connection with'sai'd mechanism, meansresponsive to the opening of said line at the said calling station foroperating said mechanism to signal a called one of said stations, meansresponsive to thecclosing of said line at the said called stationv formomentarily increasing the current flow in said line to operate the saidmagnet at the called station and for reversing the direction of currentflow in said line to operate the said device at the calling station whenthe line isagain closed thereat, andmanually controlled means at thesaid calling station for rendering it again operative for talkingpurposes.

25. In a'telephone system, a station and a line therefor, a device forrendering said station inoperative for talking purposes, an automaticmechanism, means under the control of said station for extending saidline into connection with said mechanism, means associated with saidmechanism for operating said device, and an electromagnet at saidstation for preventing the operation of said device.

26. In a telephone system, a station and a line therefor, a reversecurrent controlled device for rendering said stationinoperative fortalking purposes, a source of current for said llne, an automaticmechanism, means under the control of said station for extending saidline into connection with said mechan sm, means associated with saidmechanism fo reversing the direction of current flow in said line tooperate said device, and an electromagnet at said station for preventingthe operation of said device.

27. In a telephone system, a station and a line therefor, a device forrendering said station inoperative for talking purposes, an automaticmechanism, means under the control of said station for extending saidline nto connection With said mechanism, means associated with saidmechanism for operatmg said device, means comprising an electromagnet atsaid station for preventing the operation of said device, said lastmeans normally inoperative, and manually controlled means for restoringsaid station to operative condition. p

28. In a telephone system, a station and a line therefor, a reversecurrent controlled device for renderingsaid station inoperative fortalking purposes,'a source of current for said line, an automaticmechanism, means under the control of said station for extending saidline intoconnection with said mechi ism for reversing the direction ofcurrent fiow in said line to operate said device, an

electromagnet at said station for preventing the operation of saiddevice, said last means normally inoperative, and coin controlled meansfor restoring said station to operative condition.

'29. In a telephone system, a station and a line therefor, a device forrendering said station inoperative for talking purposes. a source ofcurrent for said line, an automatic mechanism, means under the controlof said. station fo extending said line into connection with saidmechanism, means associated with said mechanism for operating saiddevice, means at said station for preventing the operation of saiddevice, said last means comprising a normally inoperative magnetserially connected in a branch of said line, and means including asecond source of current for increasing the current flow in said branchto operate said magnet.

30. In a telephone system, a station and a .line therefor, a reversecurrent controlled device for rendering said station inoperative fortalking purposes, a source of current for said line, an automaticmechanism. means under the control of said station for extending saidline into connection with said mechanism.- means associated with saidmechanism for reversing the direction of current flow into said line tooperate said device, means at said station fol-preventing the operationof said device, said last means comprising a normally inoperative magnetserially connected in a branch of said line, and means including asecond source of current for increasing the fiow of current in saidbranch to operate said magnet.

31. In a telephone system,.a line, a pluralitvof stations in bridgethereof. a reverse current controlled device at each station forrendering its associated stat-ion inoperative for talking purposes, asource of current for said line; a selective signaling mechanism. meansunder the control of a calling one of said stations for extending saidline into connection with saidmechanism and for initiating the operationthereof, means associated with said mechanism for reversing thedirection of current flow in said line to operate said devices, and anelectromagnet at each substation for preventing the operation of itsassociated device.

' 32. In a telephone system, a line, a plu- -*'rality of stations inbridge thereof, a reverse current controlled device at each station forIendering.its associated station inoperative for talking purposes, asource of current for ttid line, a selective signaling mechanism.nit-ans under the control of a calling one of said stations forextending said line into connection with said mechanism and forinitiating the operation thereof, means associated with said mechanismfor reversing the direction of current flow in said line to operate salddevices, electromagnetlc means at each substation for preventing theoperation of its associated device. said last means normallyinoperative, and a coin collecting device at each of said stations forrendering its associated station operative for talking purposes.

'33. In a telephone system, a line, a plurality of stations in bridgethereof, a reverse current controlled device at each station forrendering its associated station inoperative for talking purposes, asource of current for said line, a selectivesignaling mechanism, meansunder the control of a calling one of said stations for extending saidline into connection with said mechanism and for initiating theoperation thereof. means associated with said mechanism for reversingthe direction of current flow in said line to operate said devices.means at each substation for preventing the operation of its associateddevice. said last means comprising a'normally inoperative magnet foreach of said stations serially connected in a branch of said line. and asecond source of current for increasing the current flow in said branchto operate one of said magnets.

34. In a telephone system. a line. a plurality of stations in bridgethereof. a reverse current controlled device at each station forrendering its associated station inoperative for talking purposes, asource of current for said line. a selective signaling mechanism. meansunder the control of a calling one of said stations for extending saidline into connection with said mechanism and for initiating theoperation thereof, means associated with said mechanism for reversingthe direction of current flow in said line to operate said devices.means at each substation for preventing the operation of its associateddevice, said last means comprising a normally inoperative magnet foreach of said stationsserially connected in a branch of said line. asecond source of current for increasing the current flow in one of saidbranches to operate one of said magnets, and

coin controlled means at each of said stations for restoring itsassociated station to operative condition.

In a telephone system, a subscribers station and a line therefor, aplurality of branches of said line at said station, a microphone'and areceiver in one branch. a reverse current controlled magnet in anotherbranch operable to exclude said microphone from said first branch. asecond magnet operative'to render ineffectual the operation of saidfirst magnet. an automatic switch accessible to said line. and relaysassociated with said switch for operating said magnets.

36. In a telephone system, a subscribers station and a line therefor,automatic switches controllable over said line from said station, aplurality of branches of said line at said station, a microphone and are ceiver in one branch, a magnet in another branch operable through themedium of one of said switches to exclude said microphone from saidfirst branch, a second magnet controllable through the medium of thesame switch for rendering the operation of said first magnetineffectual, and a coin controlled device for also rendering theoperation of said first magnet ineffectual.

37. In a telephone system, a party line and a plu 'ality of stations inbridge thereof, a reverse current controlled device at each station forrendering it inoperative. for talking purposes, a source of current forsaid line, a selective signaling mechanism, means under the control of acalling one of said stations for extending said line into connectionwith said mechanism and for initiating the operation thereof, a normallyinoperative magnet in a bridge of said line at each of said stations forpreventing the effectual operation of its associated device, a circuitassociated with said mechanism for momentarily increasing the currentflow in said line to operate the said' magnet at a called one of saidstations. and a relay associated with said mechanism for reversing thedirection of current flow in said line to operate the said device at thesaid calling station.

38. In a telephone system, a line and a plurality of stations in bridgethereof, areverse current controlled device in bridge of the line ateach station for rendering its as sociated station inoperative fortalking pur- I poses, a normally inope 'ative magnet in bridge of theline at each station for rendering the ope 'ation of its associateddevice ineffectual, a source of current'for said line, a selectivesignaling mechanism, means controllable from a calling one of saidstations for extending said line into connection with said mechanism,means responsive to the opening of said line at the same calling stationfor operating said mechanism to signal a called one of said stations,relays responsive to the closing of said line at the said called stationfor momentarily increasing the current flow in said line to operate thesaid magnet at the called station and for reversing the direction ofcurrent flow in said line to operate the said device at the callingstation when the line is again closed thereat, and a measured servicedevice at the said calling station for rendering it again operative fortalking urposes.

39. In a telep one system, the combination with a subscribers line andtalking set, of a measured service device for controlling theeffectiveness of said talking set to inling the effectiveness of saidtalking set to' inforce the assessment of a charge on each call andmeans controllable over said line for rendering the measured servicedevice ineffectual in its control, whereby the'subscriber is enabled toconverse free of charge,

and an automatic progressively movable switch controlled over said lineto extend a connection from said line to another line, said automaticswitch controlling the operation of said means.

41. In a' telephone system, the combination with'a subscribers line andtalking set, of a measured service device for controlling theeffectiveness of said talking set to inforce the assessment of a chargeon each call and electromagnetic means controllable over said line forrendering the measured service device ineffectual in its control,whereby the subscriber is enabled to converse free of charge.

12. In a telephone system, the combination with a subscribers line andtalking set, of a measured service device for controlling theeffectiveness of said talking set. electromagnetic means controlled oversaid line for rendering the measured service device ineffectual in itscontrol, an automatic progressively movable switch controlled over saidline to extend a connection from said line to another line, a source ofcurrent of one voltage for operating the switch and a source of currentof a different voltage for operating said means.

43. In a telephone system,v the combination with a subscribers line andtalking set of a measured service device for controlling theeffectiveness of said talking set, electromagnetic means controlled oversaid line for rendering the measured service device ineffectual in itscontrol, an "automatic progressively movable switch controlled over saidline to extend a connection from said line to another line, saidautomatic switch controlling the operation of said electromagneticmeans, a source of current of one voltage for operating the switch and asource of current of a different voltage for operating said means.-

44. In a'telephonesystem, the combination with a subscribers line and ameasured service deviceassociated therewith for assessing a chargeagainst the subscriber every time a call is made, of mechanismassociated with said device and controllable over the said line torender said device ineffective when a call is received.

45. In a telephone system, the combination with party lines and exchangeequipment for enabling any subscriber to call another subscriber on thesame or another line, of a measured service device at each substationfor assessing a charge against the subscriber thereat every time a callis made, mechanism associated with each device for rendering thesameinefiective, and means for operating the mechanism at a substation 10which is called from another substation on the same line to enable thesubscriber at the said called substation to converse free of charge.

Signed by me at Chicago, Cook county, 15 Illinois, this 8th day ofFebruary, 1916.

WINFRED T. POWELL.

